If you are an H-1B beneficiary and have recently received a denial or denial of a change of status, know that unlawful presence (ULP) for F-1 students will begin to accrue on the day after the request is denied (date of H-1B decision).
(ii) Nonimmigrants Admitted for Duration of Status (D/S). If USCIS finds a nonimmigrant status violation while adjudicating a request for an immigration benefit, unlawful presence will begin to accrue on the day after the request is denied. If an immigration judge makes a determination of nonimmigrant status violation in exclusion, deportation, or removal proceedings, unlawful presence begins to accrue the day after the immigration judge’s order. It must be emphasized that the accrual of unlawful presence neither begins on the date that a status violation occurs, nor on the day on which removal proceedings are initiated. See 8 CFR 239.3.
Note that this is a more favorable interpretation of ULP than the 2018 update (which is currently subject to a nationwide injunction). The 2018 update calculates ULP from the date you completed the course of study, which oftentimes is earlier than the date of H-1B filing.