bychom / bysme

As standalone second-position clitics, these auxiliaries typically occupy the second slot in a clause. However, when fused with conjunctions like aby and kdyby (forming abychom, kdybychom), the resulting word usually occupies the first slot of the dependent clause.

The Hypercorrect Trap:
A very common error—even among native speakers—is writing by jsme (or byjsme). Why does this happen? In casual spoken Czech, the j in jsme and jste is silent (pronounced sme, ste). Because the informal bysme sounds exactly like by sme, native speakers mistakenly reconstruct it in writing as two words using the present tense of the verb být. However, the present conditional uses a unique historical paradigm (bych, bys, by, bychom, byste, by). Writing by jsme is universally rejected as a severe spelling and grammar mistake. It must always be written as one word. This exact same hypercorrect mistake frequently occurs in the second person plural, where people incorrectly write by jste instead of the correct byste. Note that for the second person plural, byste is the only correct form for both formal and informal registers, and no informal equivalent exists. It also occurs in the singular, where people write by jsem instead of the correct bych and by jsi instead of the correct bys. These hypercorrect spelling errors frequently occur with conjunctions fused with the auxiliary as well (e.g., writing aby jsme, kdyby jste, or aby jsi). Remember that they must always be written as one word (abychom/abysme, kdybyste, abys). While you might hear some native speakers say bysem (and abysem / kdybysem) instead of bych, this form is highly stigmatized and associated with children or uneducated speech. As a learner, you should always stick to bych for the first person singular in all registers, even when using bysme in the plural. Additionally, when bys meets the reflexive pronouns se or si in the clitic cluster, the -s from bys detaches and fuses with the reflexive pronoun, resulting in by ses and by sis (e.g., koupil by sis, not *koupil by jsi si or *koupil bys si). Crucially, this fusion also applies to conjunctions, resulting in forms like aby ses and kdyby sis (never *abys se or *kdybys si).

Stylistic Balance:
As an advanced learner, you need to navigate these registers to become proficient in Czech. Use bychom in essays, business emails, and formal presentations. Switch to bysme when chatting with friends to sound natural and fluent.